1. Field of the Invention
Exemplary embodiments of the present invention relate to an apparatus and method for measuring three-dimensional shape by using multi-wavelength. More particularly, exemplary of the present invention relate to an apparatus and method for measuring three-dimensional shape by using multi-wavelength.
2. Discussion of the Background
In a method for measuring three-dimensional shape of a measurement object, there is a method using projection of Moire pattern. According to the method using projection of Moire pattern, a three-dimensional shape of a measurement object is obtained using a pattern image formed when a pattern light is reflected by the measurement object. In the method for measuring three-dimensional shape of a measurement object by using a pattern image, there is a phase shifting method.
According to the phase shifting method, a plurality of pattern images of a measurement object according to interference signals, is obtained moving a reference surface, and the plurality of pattern images is analyzed considering a form of the interference signal and a height of a measurement point, to measure the three-dimensional shape of the measurement object. However, the phase shifting method has a problem of 2π ambiguity.
The 2π ambiguity happens when a height difference between two adjacent measurement points is greater than a multiple of an equivalent wavelength, so that a measurement range of a measurement object is limited according to a pitch of a grating.
Therefore, when a three-dimensional shape of a measurement object is measured according to the conventional phase shifting method, a grating should be changed to correspond to the measurement object due to the 2π ambiguity.